1. Field of Invention
The present invention relates to an inductance and a manufacturing method thereof. More particularly, the present invention relates to a metal-insulating-metal transformer and the manufacturing method thereof.
2. Description of Related Art
Currently, since the transformer possesses the advantages including high efficiency, no magnetic leakage and low noise, the transformer becomes one of the essential elements in the radio integrated circuit. Moreover, the transformer is widely used in many applications such as microwave and radio frequency circuit.
The transformer is composed of a core and two coils, primary coil and secondary coil. Generally, the core is used as a medium and two coils are wound around the core. While the alternating current is applied onto the primary coil, a magnetic flux which is perpendicular to the coils is generated within the core. According to the magnetic flux within the core, a voltage is generated in the secondary coil, wherein the voltage is proportional to the number of the coils wounded around the core.
More specifically, there are two kinds of structures of the conventional transformer. One is the coplanar type and the other is the non-coplanar type. The coplanar type transformer is manufactured on the same plane. Therefore, the size of the coplanar type transformer is too large so that size of the radio circuit with the coplanar type transformer is lager as well. Therefore, the cost is high. Furthermore, for the non-coplanar, the space between two coils is relatively large so that the coupling coefficient of the transformer is low. Hence, the performance and the reliability of the device are seriously affected.
With the decreasing of device size, the conventional transformer and the conventional method for manufacturing the transformer cannot full fill the design requirements. Therefore, how to overcome the over size problem and to effectively decrease the size of the transformer become the main task of the present technology development.